GitLab has a great issue tracker but you can also use an external one. External issue trackers are configurable per GitLab project.
Once configured, you can reference external issues using the format
CODEis a unique code for the tracker.
123is the issue number in the tracker.
These references in GitLab merge requests, commits, or comments are automatically converted to links to the issues.
You can keep the GitLab issue tracker enabled in parallel or disable it. When enabled, the Issues link in the GitLab menu always opens the internal issue tracker. When disabled, the link is not visible in the menu.
The configuration is done via a project’s Settings > Integrations.
To enable an external issue tracker you must configure the appropriate Integration. Visit the links below for details: